Very well. The point protected here at
"Coke Ovens" happens to be a siding, and
we now stand, if you please, at the protected
point. Three hundred yards distant from it,
or it may be five hundred yards, there is
erected the signal post, on one side of the line.
The telegraph is worked by a lever at this
point where the rails join, and the lever is so
contrived that, when set at "All right,'' it
acts as a lock which keeps the two sets of rails
apart from one another. To unite the rails
for the purpose of moving a truck or
anything else, out of the siding here to the main
line, it is necessary so to move the lever as to
set the telegraph to "Danger;" leaving the
after signal of "All Right," an act of discretion
in the guard, but not leaving it possible for
him to omit the immediate sign of peril.
Furthermore, the levers and weights
connected with the telegraph are so arranged,
that "All Right" is a constrained position, to
which the lever at the siding has to be pulled
and set, and that if any accident should occur
to the wires, the telegraph would relapse at
once to "Danger." So that, while such
an accident might for a few minutes delay a
train, by causing the driver to shut off his
steam, it could not possibly imperil life. The
whole signal apparatus is so thoroughly
simple, however, that it is no more likely to
get out of order, than a kettle-bottom is likely
to wear into a cullender; there is nothing
to look at but the wear and tear of the
material.

Now we will walk towards the signal post.
Near it, we see fixed beside the rail a little
spring. Upon this spring every train, without
exception, presses as it goes by, and the
pressure instantly sets on the telegraph the
"danger" signal. Thus, a train takes out of
fallible hands the warning to expresses and
others not to run in upon it, and the "danger"
signal so set, remains fixed for so many
minutes as it is thought fit and safe should
be the smallest intervening time between the
passage of two trains over one spot. The
signal man restores "All Right," when it is
proper that he should do so.

Now we have passed the signal post, and
are continuing our walk along the line
towards the locomotive, which is just in sight,
steaming to meet us. About one hundred
yards beyond the telegraph, our attention is
called to a couple of double wedges, or double
inclined planes, placed side by side, which
play up and down out of a little hollow
close beside the protected line of rail. These
little wedges, when the telegraph is fixed at
"All Right," are, by the same act, both
depressed; they duck their heads together.
But at the sign of "caution," one of them bobs
up; and they both bob up at the sign of
"danger."

There is the locomotive stopping for us;
we will go and look, in the next place, at
that. To one side of it, is attached a little
apparatus in a box, not unlike a folded
carriage-step, and scarcely larger. Two little
triggers hang down from it to within a little
distance from the ground. One of these
triggers, we should say, the steam being shut
off, does not hang down, but tucks itself
back like a crane's leg. When the engine is
in motion, the steam being on, this leg drops,
and the two legs hang down. When the
driver, however, shuts off his steam, one leg
is immediately tucked away. Now these two
legs or triggers are connected with an
extremely simple series of rods and levers, and
they are calculated to run over the two little
wedges which we just now examined. One
little wedge being up, touches the key, or leg,
or trigger of "caution," as the train passes, and
the striking of that key lets loose a volume of
steam through a whistle, loud enough to
startle up the sleepiest of engine-drivers.
The other little wedge being up, touches
the key of "danger;" but, mind! a trigger
ought not to have been touched. Fog
hail, or other causes, may have prevented
the driver from perceiving, in good time, the
warning on the telegraph; if he has seen it,
he shuts off the steam before he gets near
the little wedge, and as he shuts the steam off,
up goes the little "danger" leg, and rides
untouched over its wedge, while the "caution"
wedge, which is always up in company with
"danger," sets only the whistle going. If,
however, it should happen that the driver has
neglected to shut off his steam, the "danger"
key remains down and is struck; immediately
a lever rolls over untouched by the driver's
hand, the engine is reversed, the steam shut
off, and the break is put upon the wheels. At
the same time a hand moves upon a dial, and
records that it was not to the driver, but
to the safety apparatus, that the stoppage of
the train was due.

A plan had once been tried for the mechanical
sounding of a "caution" whistle by means
of a trigger; but the trigger not being made
to glide up an inclined plane, but to strike
upon an abrupt obstruction, generally either
snapped off, or kicked the obstacle before it
on the line of rail.

We now station ourselves beside the little
wedges, set the "danger" signal, and bid the
locomotive rush at it, steam on. Instantly, as
it touches the appointed spot, the whistle
sounds, the pace begins to slacken, and before
the engine reaches the protected siding, it is
still standing upon the line. We run the
engine back, and mount into the tender. We
watch the handle, which is to move untouched
by human hands. We whiz through the cold
October air; a deafening shriek, a rush of
steam, and the rolling over of the handle,
startle us; the whistle is indefatigable; but
the engine seems fatigued, and very shortly
we are brought to a dead stop.

This experiment was repeated and modified,
the result being at all times a complete
success. Having since that day looked over
the drawings and the working plans, we feel